PPRuNe Forums - View Single Post - BASI "Limitations of See & Avoid" ??
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Old 8th Aug 2003, 19:42
  #18 (permalink)  
Join Date: Jun 2003
Location: Awstraya
Posts: 194
Like that handle - "WhatWasThat"

If you read my posts, you'll see we agree on the unreliability of see and avoid in all but the most structured environments.

We also agree that ACFT tracks are semi-random, as I have said above in previous postings, and as you say. They are "micro-modified" by things such as compass, DG, pilot and altimeter accuracy which give significant random variation to the actual 3-D path followed through the sky. In addition, those using coupled TSO'ed GPS's usually have a track offset to avoid oncoming..... Even with the "corridors" you suggest, there is a significant scope for random variation.

The places (especially outside C towers) which are frequently travelled by IFR ACFT are also more frequently travelled by VFR ACFT. Some of these places are CTAF's, some are MBZ's. There are plenty of spots where climb/descent/en-route IFR ACFT mix it with VFR ACFT and other IFR ACFT where they will not necessarily be on the same frequency (or otherwise be incapable of hearing each other), may not be visible on ATC radar, may not have TCAS/TXP's. For example, think Temora on a museum flying weekend with arrival/departures of jets/turbine/light GA/ultralights. Why then is there not a history of en-route midairs (or even climb/descent midairs) if such situations are common and we agree that see and avoid is so fallible????

How far is a minute ahead? Depends on the closing speeds - head on at 200KTS (i.e. 2 Skyhawks!) its 6 km, for 400 KTS its 12 km - that's a lot, really. If overtaking, can be very close indeed. Exactly what *distances* (not time) are you able to discriminate?

Bear in mind that sometimes one reason IFR pilots talk to each other when given the opportunity is not for pure operational reasons, but because John Laws or the country music on the ADF is boring them!!

Safe flying

NOtimTAMs is offline